Subsea foundation unit and method of installation

ABSTRACT

The specification discloses a subsea foundation unit for use in drilling and completing a plurality of submerged wells particularly in areas where the marine bottom slopes or is uneven. The unit is comprised of a base and a drilling and completion template. The unit is lowered in the water until the base engages the marine bottom. The template is adjusted with relation to the base until the template is substantially level. Next, the template is secured to the bottom and is released from the base. The base is removed leaving only the leveled template on the bottom.

United States Fatent Manning June 27, 1972 [54] SUBSEA FOUNDATION UNET AND 3,294,051 12/1966 Khelstovsky ..6l/46.5

METHOD OF ENSTALLATHON Primary Examiner-Jacob Shapiro [72] Inventor William Manning Dallas Attorney-William J. Scherback, Frederick E. Dumoulin, [73] Assignee: Mobil Oil Corporation Drude Faulconer, Andrew L. Gaboriault and Sidney A. John- 22 Filed: June 24, 1970 [21] Appl. No.: 49,372 [57] ABSTRACT The specification discloses a subsea foundation unit for use in [52] US. Cl ..6l/46.5, 175/7, 175/9 drilling and completing a plurality of submerged wells particul f E02) 17/03 larly in areas where the marine bottom slopes or is uneven. Field of Search 46, l75/7, The unit is comprised of a base and a drilling and completion 175/8 10; D template. The unit is lowered in the water until the base engages the marine bottom. The template is adjusted with rela- [56] References C'ted tion to the base until the template is substantially level. Next, UNITED STATES PATENTS the template is secured to the bottom and is released from the base. The base is removed leaving only the leveled template 2,968,930 l/l96l Mangone ..6l/46.5 on h bottom 2,430,014 11/1947 14 Claims, 4 Drawing Figures PATENTEDJum 1972 3.672177 sum 1 or 2 WILLIAM F. MANNING MINVENTOR ATTORNEY PATENTEDJUMN 1972 SHEET 2 BF 2 FIG. 4

WILLIAM F. MANNING ATTORNEY SUBSEA FOUNDATION UNIT AND METHOD OF INSTALLATION BACKGROUND OF THE INVENTION The present invention relates to an apparatus for use in drilling and completing submerged wells and to a method for installing said apparatus in an underwater environment. More particularly, the invention relates to a drilling and completion template which can be effectively leveled on a sloping marine bottom.

One of the most proven techniques for recovering minerals from underwater deposits utilizes a bottom-supported, abovesurface platform. The platform is first used to drill and complete wells and then is adapted to support production facilities for producing said wells. However, as the depth of the water increases, the building and installing of a bottomsupported platform becomes prohibitive from a technical and cost standpoint. Further, even in shallow water, fixed platforms have certain disadvantages, e.g., they are susceptible to wind and wave damage; they present a hazard to navigation in some areas; and they detract from the natural beauty of some locales.

In the past several years, other techniques which do not require the use of a fixed platform have been developed or proposed for producing underwater deposits. One such technique involves the drilling and completing of a plurality of submerged wells through a single template structure which is affixed on the marine bottom. Two examples of such a technique are disclosed in the present inventors U.S. Pat. No. 3,504,740, issued Apr. 7, 1970 and his copending application Ser. No. 663,798, filed Aug. 28, 1967. However, in using submerged templates, serious difficulties often arise in aligning drilling and completion equipment from the surface through the guides on the template when the template is affixed to a marine bottom which is uneven or slopes at a substantial angle with respect to the earth's horizon. Therefore,.it is desirable to provide some means for substantially leveling the template structure on the marine bottom with respect to the horizon be fore the drilling operations are commenced.

SUMMARY OF THE INVENTION The present invention provides .a subsea foundation unit which includes a drilling and completion template structure that can be effectively leveled on a sloping or uneven marine bottom.

Structurally, the foundation unit is comprised of a base structure and a template structure. The template structure is comprised of a plurality of conductor pipe jackets connected to each other within an open framework. The template is attached to the base structure by flexible lines which are operably connected to winches mounted on the base structure. Selected conductor pipe jackets have retracted piles which usually double as conductor pipes releasably secured therein which are released and then caused to penetrate the marine bottom in order to anchor the template to the marine. bottom once the template has been properly positioned.

To place the template structure in its proper position, the foundation unit is lowered to the marine bottom. The base structure will contact the marine bottom and will attain a position relatively parallel to the marine bottom. If the marine bottom is uneven or slopes, both the base and the template will normally slope also. Line from one or more of the winches is played out or taken in to adjust the template with relation to the base and this maneuver is continued until the template structure is located near the ocean bottom and effectively leveled with respect to the horizon. This is determined directly or remotely from level indicating means mounted on the template structure.

When the template structure is in position, the piles are released from their respective jackets and naturally fall to engage the marine bottom. Once the piles are securely in place as a result of appropriate driving and/or drilling procedure, the template is releveled, if necessary, by further operation of the winches. A positive connection is then made between the pile and its respective jacket by means of a ballistic connection, grouting, or the like. The flexible lines are released from the now anchored template structure or alternately released from the winches and the base structure is removed. The result is a relatively level template structure fixedly secured to the marine bottom which is ready for use in drilling and completing submerged wells.

The actual construction, operation, and the apparent advantages of the present invention will be better understood by referring to the drawings in which like numerals identify like parts and in which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is an elevated view of the present invention as it originally engages a sloping marine bottom;

FIG. 2 is a plan view taken along section line 2-2 of FIG. 1;

FIG. 3 is an elevational view of the apparatus of FIG. 1 with the template in an adjusted position; and

FIG. 4 is an elevational view of the template in its final position.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring more particularly to the drawings, subsea foundation unit 10 is comprised of a base structure I l and a drilling and completion template 12. Base structure 11 is comprised of a plurality of legs 13 which are connected together by means of members 14 to form an open frame. Only three legs have been shown, but it should be understood that more than three could be used without departing from the present invention. Each leg I3 has a footing 15 on the lower end thereof which is adapted to engage the marine bottom when unit 10 is lowered in a body of water.

Conductor pipe template 12 is comprised of a plurality of conductor pipe jackets 18 which are connected together by brace members 19 to form an open framework. Each of said conductor pipe jackets 18 is normally adapted to guide a conductor pipe (not shown) from the surface into the marine bottom which in turn is used in drilling and completing a well therethrough. A central element 20 is secured into the open framework of template 12 by means of radial struts 21 (FIG. 2). Element 20 provides means for attaching a production satellite (not shown) to template 12 for producing wells which have been drilled and completed through jackets 18. For an example of how wells are drilled and completed through template guides such as jackets 18 and also for an example of a satellite which can be used and the manner in which it can be installed and attached on a template, see inventors U.S. Pat. No. 3,504,740, issued Apr. 7, 1970. Although the use of a satellite is preferred, it should be realized that the template of the present invention need not include means 20 for attaching a satellite since other manifolding or production systems could be used without departing from the invention. Files 25 are slidably positioned in selected conductor pipe jackets l8 and are normally held in a retracted position within their respective jackets (FIGS. 1 and 2) by any known means, e.g., explosive bolts 26 (as shown in FIG. 1). Three piles have been shown in FIG. 2, each equally spaced from the others, but this number or placement should not be considered limiting since the number and placement could be varied depending on the template 12 configuration and the actual environment in which it is used. Piles 25 could be solid members but preferably are hollow conductor pipes through which wells can be drilled and completed. A ballistic unit 27 such as that fully disclosed and described in inventors U.S. Pat. No. 3,352,119, issued Nov. 14, 1967, is provided on each of jackets 18 in which a pile 25 is mounted. As will be explained below, unit 27 is used to connect pile 25 to its respective jacket 18 after said pile is in its operable position.

Template 12 is adjustably and releasably connected to base 11 by means of flexible lines 30 which are in turn operably connected to winches 31. Winches 31 are preferably equally spaced on base 11 and each is operated by a power means 32. Preferably, power means 32 is a remotely controlled, hydraulic motor but any type of power means which could operate in a subsea environment could be used. Lines 30 are connected to template 12 by any releasable means, e.g., safety hooks 33 on lines 30 which cooperate with eyes 34 on template 12. Another technique which can be employed to release template 12 from base 11 is to permanently attach lines 30 to template 12 and then play off the lines from their respective winches once the template is anchored. Level indicating means 35 (FIG. 2) are positioned on template [2 for indicating the relative position of template 12 with respect to the earth's horizon. Means 35 are preferably of the type which generate signals that can be relayed and observed on the surface (e.g., Vertimeter" manufactured by The Rucker Company), but simple bubble" gauges which may be observed by divers or personnel from submerged work vessels also may be used.

Template 12 may be installed as follows. Subsea foundation unit is lowered in a body of water 40 until footings on legs 13 of base structure 11 engage marine bottom 41 which is shown in the drawings as sloping at a relatively steep angle with respect to the horizon as represented by the water surface 39. Unit 10 may be lowered by any known means such as cables or a special handling structure such as shown in inventors U.S. Pat. No. 3,504,740 may be used. As footings 15 engage bottom 41, unit 10 will attain a position substantially parallel to bottom 41 but one which is at a steep angle with respect to the horizon.

Power means 32 on winches 31 are selectively actuated to play out and/or take in lines 30, as needed to allow template 12 to attain a position near the bottom 41 and relatively parallel to the earth's horizon 39 (see FIG. 3). Since the lines are flexible, template 12 can move laterally as well as vertically so the leveling on template 12 is readily accomplished. After template 12 has been leveled, as determined from level indicating means 35, piles 25 are released from their respective jackets 18. This is done by actuating explosive bolts 26. When the piles are released, they will fall to the marine bottom and probably will penetrate into same. Files 25 may be driven into bottom 41 by submerged pile drivers or they may be washed or drilled into place as is known in the art. In some instances, e.g., the piles are washed or drilled into place, it may be desirable to cement the piles into marine bottom 41 while in other instances this may be unnecessary. Standard oil well cementing techniques can be used to cement the pile and are well within the skill of the art.

After piles 25 are firmly in place in marine bottom 41, level indicating means 35 are checked to see if template 12 is still level. If not, template 12 is brought back to a level position by further selective operation of winches 31. Ballistic units 27 are then actuated to form a firm connection between pile 25 and its respective jacket 18. Usually, a more secure connection is desired between pile 25 and jacket 18. Also, a firm connection is desired between the remaining jackets l8 and their respective, subsequently installed conductor pipes (not shown). For this reason, a seal means 28 (FIG. 1) is provided at the lower end of all of jackets 18. Seal means 28 allows pile 25 to slide therethrough but provides an effective seal therewith to close the annulus within the jacket. Grout is then pumped into jacket 18 through line 29 and is allowed to set to solidly connect pile 25 to its jacket. Other times, grout alone may be used for the connection, in which event ballistic unit 27 is not used. Further, in some instances, seal means 28 is an inflatable, annular member which can also function as the means for retaining piles 25 in their retracted positions. Seal 28 is inflated to frictionally hold pile 25 in said retracted position, partially deflated to allow the pile to drop to the marine bottom, and then reinflated to seal the annulus between the pile after the pile has been finally positioned in the marine bottom.

With leveled template 12 now securely attached to marine bottom, lines 30 are released from the template. This may be done by divers or by providing frangible hooks or eyes which are designed to shear when winches 31 are actuated while the template is secure. As mentioned above, if lines 30 are permanently attached to template 12, lines 30 are merely played off their respective winches. Base structure 11 is then removed back to the surface. Files 25 usually will be cut off at an elevation compatible with future use. What remains is a leveled template (see FIG. 4) which is ready for utilization in the drilling and completing of a plurality of submerged wells.

Although a specific embodiment has been disclosed for illustrative purposes, it should be recognized that modifications may be made without departing from the present invention. For example, while flexible lines and winches have been shown as the preferred means for adjusting the template relative to the base, other means could be used, e.g., hydraulic cylinders pivotably mounted on the base and their respective cooperating piston rods pivotably and releasably connected to the template. Further, special jackets which differ from the other jackets on the template could be used to house the piles. Still further, hydraulically or explosively actuated means could be used to releasably secure lines 30 to template 12.

What is claimed is:

l. A fully submergible subsea foundation unit comprising:

a base structure adapted to be positioned on a marine bottom in a fully submerged position within a body of water;

a drilling template having a plurality of drill guides thereon through which subsea wells may be drilled and completed;

means for releasably connecting said drilling template to said base structure so that said drilling template will be positioned on the marine bottom in a fully submerged position with said base structure; and

means for adjusting the angular relationship between said drilling template and said base structure.

2. The fully submergible subsea foundation unit of claim 1 including:

means for affixing said template structure to a marine bottom when said template structure is in its desired position.

3. The fully submergible subsea foundation unit of claim 1 wherein:

said means for releasably connecting said drilling template to said base structure comprises flexible line means connected to said template; and

said means for adjusting said drilling template comprises winch means mounted on said base, said flexible line means being operably connected to said winch means.

4. The fully submergible subsea foundation unit of claim 2 wherein said drilling template comprises:

a plurality of conductor pipe jackets which comprise said drill guides; and

means connecting said conductor pipe jackets together in a spaced relationship with respect to each other.

5. The fully submergible subsea foundation unit of claim 4 wherein said means for affixing said template structure to a marine bottom comprises:

piles slidably positioned in some of said plurality of conductor pipe jackets; and

means to releasably hold said piles in a retracted position within their respective conductor pipe jackets.

6. The fully submergible subsea foundation unit of claim 5 including:

means to secure said piles to their respective conductor pipe jackets after said piles have been released from their retracted positions.

7. The fully submergible subsea foundation unit of claim 6 wherein:

said piles are hollow, conductor pipes which can be used for drilling and completing wells.

8. The fully submergible subsea foundation unit of claim 1 wherein said base structure comprises:

a plurality of legs, and

means connecting said legs together in a spaced relationship to form a polygon-shaped framework with one of said legs at each angle of said polygon-shaped framework;

and wherein:

said drilling template comprises:

a plurality of conductor pipe jackets which comprise said guide means, and

means connecting said conductor pipe jackets together in a spaced relationship with respect to each other.

9. The fully submergible subsea foundation unit of claim 8 wherein said means for releasably connecting said drilling template to said base structure and said means for adjusting said drilling template with respect to said base structure comprises:

a plurality of winch means mounted on said base structure, each of said winch means being spaced from its respective adjacent winch means; and

a flexible line for each of said winch means, each line having one of its ends operably connected to its respective winch means and having its other end attached to said drilling template.

10. A method of installing a fully submergiblc subsea foundation unit on a marine bottom wherein said unit comprises a base portion with a template portion releasably connected thereto, said method comprising:

a. lowering said foundation unit until it is completely submerged with said base portion resting on said marine bottom;

b. adjusting said template to a desired angular position above the marine bottom with relation to said base portion;

c. securing said template to said marine bottom while said template is fully submerged in said desired position; and

d. releasing said base portion from said template portion.

ll. The method of claim 10 including:

removing said base portion from said marine bottom after it has been released from said template.

12. A method of installing a fully submergible subsea foundation unit on a marine bottom wherein said unit comprises a base portion with a template portion attached thereto, said template portion comprising a plurality of spaced conductor pipe jackets connected together, said method comprising:

a. lowering said foundation unit until it is completely submerged with said base portion resting on said marine bottom;

b. adjusting said template to a desired position with relation to said base portion;

c. positioning piles through selected conductor pipe jackets and into said marine bottom; and

d. securing said piles to their respective conductor pipe jackets to effectively anchor said template to said marine bottom in said desired position.

13. The method of claim 12 wherein the following steps are performed between steps (c) and (d):

checking the desired position of said template after said piles have been positioned; and

readjusting said template to said desired position if said template has moved therefrom 14. The method of claim 12 including:

detaching said template from said base portion after said template has been anchored to said marine bottom; and

removing said base portion from said marine bottom.

i i t 

1. A fully submergible subsea foundation unit comprising: a base structure adapted to be positioned on a marine bottom in a fully submerged position within a body of water; a drilling template having a plurality of drill guides thereon through which subsea wells may be drilled and completed; means for releasably connecting said drilling template to said base structure so that said drilling template will be positioned on the marine bottom in a fully submerged position with said base structure; and means for adjusting the angular relationship between said drilling template and said base structure.
 2. The fully submergible subsea foundation unit of claim 1 including: means for affixing said template structure to a marine bottom when said template structure is in its desired position.
 3. The fully submergible subsea foundation unit of claim 1 wherein: said means for releasably connecting said drilling template to said base structure comprises flexible line means connected to said template; and said means for adjusting said drilling template comprises winch means mounted on said base, saiD flexible line means being operably connected to said winch means.
 4. The fully submergible subsea foundation unit of claim 2 wherein said drilling template comprises: a plurality of conductor pipe jackets which comprise said drill guides; and means connecting said conductor pipe jackets together in a spaced relationship with respect to each other.
 5. The fully submergible subsea foundation unit of claim 4 wherein said means for affixing said template structure to a marine bottom comprises: piles slidably positioned in some of said plurality of conductor pipe jackets; and means to releasably hold said piles in a retracted position within their respective conductor pipe jackets.
 6. The fully submergible subsea foundation unit of claim 5 including: means to secure said piles to their respective conductor pipe jackets after said piles have been released from their retracted positions.
 7. The fully submergible subsea foundation unit of claim 6 wherein: said piles are hollow, conductor pipes which can be used for drilling and completing wells.
 8. The fully submergible subsea foundation unit of claim 1 wherein said base structure comprises: a plurality of legs, and means connecting said legs together in a spaced relationship to form a polygon-shaped framework with one of said legs at each angle of said polygon-shaped framework; and wherein: said drilling template comprises: a plurality of conductor pipe jackets which comprise said guide means, and means connecting said conductor pipe jackets together in a spaced relationship with respect to each other.
 9. The fully submergible subsea foundation unit of claim 8 wherein said means for releasably connecting said drilling template to said base structure and said means for adjusting said drilling template with respect to said base structure comprises: a plurality of winch means mounted on said base structure, each of said winch means being spaced from its respective adjacent winch means; and a flexible line for each of said winch means, each line having one of its ends operably connected to its respective winch means and having its other end attached to said drilling template.
 10. A method of installing a fully submergible subsea foundation unit on a marine bottom wherein said unit comprises a base portion with a template portion releasably connected thereto, said method comprising: a. lowering said foundation unit until it is completely submerged with said base portion resting on said marine bottom; b. adjusting said template to a desired angular position above the marine bottom with relation to said base portion; c. securing said template to said marine bottom while said template is fully submerged in said desired position; and d. releasing said base portion from said template portion.
 11. The method of claim 10 including: removing said base portion from said marine bottom after it has been released from said template.
 12. A method of installing a fully submergible subsea foundation unit on a marine bottom wherein said unit comprises a base portion with a template portion attached thereto, said template portion comprising a plurality of spaced conductor pipe jackets connected together, said method comprising: a. lowering said foundation unit until it is completely submerged with said base portion resting on said marine bottom; b. adjusting said template to a desired position with relation to said base portion; c. positioning piles through selected conductor pipe jackets and into said marine bottom; and d. securing said piles to their respective conductor pipe jackets to effectively anchor said template to said marine bottom in said desired position.
 13. The method of claim 12 wherein the following steps are performed between steps (c) and (d): checking the desired position of said template after said piles have been positioned; and readjusting said template to said desired position if said template has moved therefrom.
 14. The method of claim 12 including: detaching said template from said base portion after said template has been anchored to said marine bottom; and removing said base portion from said marine bottom. 